Round zucchini: A growing guide from seed to harvest

Zucchini is one of the most popular vegetables grown in home gardens because it’s easy, productive, and delicious. There are many types and varieties to try with a wide range of fruit colors and shapes; from cylindrical to scallop to crookneck to round. They offer subtle differences in flavor and texture as well as kitchen use. In our garden, round zucchini varieties have become a favorite for their novel shape and bright colors. Read on to learn more about planting and growing round zucchini.

What are round zucchini?

Zucchini, or summer squash, is a warm season vegetable in the squash and pumpkin family with fruits that are harvested when immature and very tender. Round zucchini varieties like Eight Ball and Piccolo are best picked small, from one to four inches across, and can be enjoyed in the same way as all types of zucchini – grilled, sautéed, roasted, and baked. The round shape makes this vegetable perfect for hollowing out and stuffing with meats, vegetables, rice, and herbs.

When to plant round zucchini

Zucchini is a heat-loving vegetable and sensitive to cold weather and frost. Don’t rush the season by seeding or transplanting too early. Wait until the soil has warmed to 65-70 F (18-21 C); about a week or two after the last expected frost. If the temperature takes a dip after you’ve seeded or transplanted zucchini, use cloches or a row cover to protect the plants. Learn more about row cover hoops in this article.

How many plants do you need?

Let’s be honest, zucchini is PRODUCTIVE! You don’t need a lot of plants to enjoy a steady supply all summer long. Two plants is probably enough for a family of four, but if you’re big on zucchini you may wish to plant an extra to share with extended family, friends, neighbors, or your local food bank.

Planting round zucchini

All types of summer squash, including round zucchini can be direct sown in the garden or started indoors under grow lights. Zucchini grow best when planted in a sunny spot with well-draining soil that has been amended with compost or aged manure. Avoid adding high nitrogen fertilizers to the planting site as that promotes vigorous leafy growth but few fruits.

How to direct sow

Once the weather has settled and the soil has warmed up direct seed in garden beds, hills (see more below), or containers. I’ve had great success with large fabric grow bags and beds. If growing in rows or raised beds, plant seeds a half inch to one inch deep spacing them every six inches. Thin to eighteen inches apart once the seedlings are growing well. Space rows four feet apart. Keep newly planted seed beds consistently watered to promote good germination. If cold weather threatens, cover the bed with a length of row cover.

Starting the seeds indoors

Zucchini are very quick to grow and only need to be seeded indoors three to four weeks before they’re moved to the garden. Because the seedlings size up fast, plant the seeds in four inch pots filled with a high-quality potting mix. Sow the seeds a half inch deep and place the containers in a sunny window or beneath grow lights. If using grow lights, keep them on for sixteen hours a day. You can use an inexpensive timer to turn the lights on and off if you’re forgetful – like me!

As the seedlings grow, pay attention to soil moisture, watering when the growing medium is dry to the touch. Don’t overwater though, try to maintain a lightly moist soil. I also give my seedlings an application of a liquid organic fertilizer diluted to half strength once the second set of true leaves appears.

Around the last frost date, I begin the hardening off process by setting the plants outdoors in a shady site. Over the next few days, I gradually introduce them to more sunlight until they’re acclimatized and ready to be transplanted into the garden.

How to plant zucchini in hills

There are many ways to grow zucchini; in an in-ground garden, raised bed, straw bale garden, container, or in a hill. Hills are low mounds made by hilling up the soil in a garden. There are a several benefits to planting zucchini in hills:

• Early warm up – Soil raised in hills warms up quicker in spring which heat-loving zucchini appreciate. 
• Soil fertility – Growing in hills allows you to control the quality of the soil, adding extra organic matter for greedy summer squash plants. 
• Drainage – Hills provider better drainage than in-ground gardens.
• Pollination – There are typically several zucchini plants grown in each hill. Having plants grouped together improves the chances of pollination.   

Planting in hills is easy and ideal for in-ground gardens. Use a hoe or garden spade to form a low mound about 12 to 18 inches across. If making more than one hill, space them four feet apart. Sow three to four seeds per hill, eventually leaving only the two strongest seedlings.

Succession plant for the longest harvest

After about six weeks of production, I find zucchini plants begin to slow down. To ensure we have the longest season of tender fruits, I succession plant more seeds in mid summer. This second crop provides us with a heavy harvest of round zucchini until frost. Select a variety that has enough time to grow and produce before the arrival of the fall frost. Most varieties of round zucchini start producing about fifty days from seeding. 

Growing round zucchini

Summer squash is pretty low maintenance but deep water the plants weekly if there has been no rain. When watering I use a watering wand to direct the flow of water to the base of the plant. Avoid wetting the leaves which can spread disease. I also mulch my plants with a layer of straw to hold soil moisture and reduce watering.

Keep an eye out for potential pests like squash bugs and diseases like powdery mildew. For more information on zucchini pests and diseases, check out this detailed article by Jessica.

How to pollinate summer squash

A common issue when growing zucchini is having lots of flowers but no fruits forming. This is typical when the plants first begin to bloom. Initially zucchini plants produce a lot of male flowers but few, if any, female flowers. No girl blooms means no fruits. In this case your only option is to be patient. Female flowers usually start to appear a week or two after the male flowers.

Because zucchini plants have separate male and female flowers pollen must be transferred from a male flower to a female flower for pollination to take place. This usually happens via bees and other pollinators, but if the weather has been cool, rainy, or you don’t have a lot of bees visiting your garden, pollination rates may be low. You can help out by hand pollinating when you notice newly opened male and female flowers. Learn how to hand pollinate in this article.

When to harvest round zucchini

As a kid I remember the zucchini plants in our garden yielded massive, baseball bat sized fruits which were tough, woody, and seedy. My mother would shred these up for zucchini loaves and cakes, but we rarely ate zucchini as a vegetable. Today we eat zucchini all summer long, harvesting the fruits within days of pollination when they’re immature, super tender, and delicious. Round zucchini can be harvested between one and four inches across for grilling, baking, or sautéing. If you want to use the ball-shaped fruits as a soup bowl, let them grow six or eight inches in diameter and then hollow them out.

If you go away for a couple of days and missed harvesting your fruits at the optimal time, remove them anyway. Leaving overmature fruits on the plant slows production. Don’t pull or twist fruits from the plants. This can bruise or damage them. Instead, use garden snips or pruners to clip them from their stems. Learn more about when to pick zucchini.

Don’t forget the flowers! Summer squash blooms are edible and can be dipped in tempura batter and flash fried, or stuffed with cheese and herbs for a summer treat.

Before I introduce you to some of the best varieties of round zucchini to grow, watch this quick tutorial on a clever way to get rid of squash bugs:

Best varieties of round zucchini to grow

There are many round zucchini varieties available through seed catalogs. You may even spot them on the seed racks at your local garden centre. There are both hybrid as well as open-pollinated options, but I’ve found hybrids like Cue Ball to be more disease resistant than heirloom zucchinis. Below are some of the favourites that I’ve grown in my garden:

The Ball Series:

This trio of summer squash hybrids offer excellent vigor, disease resistance, and high yields. Eight Ball was introduced in the 1990’s and quickly became popular among home and market gardeners. The cultivars offer continuous fruit set over a long harvest season and an open plant structure for easy harvesting. 

• Eight Ball (50 days) – Perhaps the best known round zucchini, Eight Ball has dark green skin and tender, buttery flesh. It’s also an All-America Selections winner for its many outstanding characteristics: early yield, large harvest, excellent flavor, and versatility.
• Cue Ball (48 days) – The glossy fruits of Cue Ball have pale green skin with white speckles. The flesh is very tender, especially if the round zucchinis are picked when just a couple of inches across. The plants are resistant to Yellow Mosaic Virus.
• One Ball (48 days) – This is my favorite of the Ball Series. I love the sunny yellow fruits that are smooth and glossy and the high productivity of the plants. The compact bush habit of those plants makes this a good choice for containers or small spaces. 

Other round zucchini varieties:

Lucky 8 (48 days) – Lucky 8 is an early maturing variety with the harvest beginning just 7 weeks from seeding. Each fruit is perfectly round with dark and light green streaks and speckles. Beautiful and delicious.

Piccolo (55 days) – I’ve grown Piccolo several times over the past few years and been very impressed with the productivity and compact growth of the plants. They’re also spine-free – no scratches when harvesting! The gorgeous egg-shaped fruits have alternating dark and light green stripes and look like miniature watermelons. Pick when they’re two inches across and three inches long.

Ronde de Nice (53 days) – A French heirloom, Round de Nice has beautiful gray-green speckled fruits. The rich flavor of the tender flesh makes this open-pollinated variety a standout. 

Lemon (55 days) – Ok, technically this isn’t a round zucchini, but it’s a kinda round zucchini with fruits that look like lemons. It’s a big hit in our garden and we pick the unique fruits when they’re about the size of a lemon – 2 inches across and 3 inches long. Expect heavy yields on robust plants. Lemon Drop is a similar variety with glossy yellow fruits. 

For more reading on growing squash and related veggies, check out these articles:

• Zucchini companion plants for the vegetable garden
• Cucumber plant spacing for high yields in gardens and pots
• Growing spaghetti squash: from seed to harvest
• Growing loofah gourds: learn how to grow your own loofah sponges

Are you growing round zucchini in your vegetable garden?